The present invention relates to a sinker mechanism for flat knitting machines.
The sinker mechanisms for flat knitting machines of prior art are characterized in that multiple knitting needles are placed in parallel and have the capability of sliding in and out of the needle bed, and that each sinker is fixed to the needle bed, its tip being located between adjacent knitting needles.
In the prior art, a previously formed loop is held by the sinker, but if the knitting width must be expanded abruptly--during fashioning, for example--a takedown device will pull the narrow-width loop with great force, whereas the force applied to press down the first course of loops is insufficient, resulting in uneven loops.
To remedy this problem, a so-called "waste course" was used so the knitting could be adjusted gradually to the required width. This "waste course" tended to reduce productivity.
German patent application DE 3917934 solved the problem of the "waste course" by making sinkers capable of rocking.
In that patent, the sinker is characterized in that it is J-shaped and supported by a pin in the middle with a press-down part at the end near the knitting needle which positions loops, and with a spring support projecting from one part of the sinker. This spring support allows abrupt widening without going through a "waste course."
However, such a sinker presented the disadvantage of being too high and bulky because its movement is controlled by cams on the carriage and because it has a pin in the middle of the J shape.
In addition, since its spring support is part of the sinker, it is made of the same material as the sinker, and the spring modulus cannot be adjusted. This is a serious defect in a knitting machine designed to produce varieties of patterns. Moreover, since the sinker has a pin in the middle, replacing it is a problem: when the pin is pulled out, the sinker pops out because of its spring support. Installation of the sinker requires substantial time and effort because of this spring support's tendency to pop out the sinker.
The object of the present invention is to provide a sinker mechanism for flat knitting machines that obviates these shortcomings; in addition to improving productivity by eliminating the "waste course" step, it also applies the proper tension to the loops regardless of the type of yarn used.